Swedish climate campaigner Greta Thunberg was detained by the British police in central London on Tuesday, where she and other activists had gathered to protest outside a major oil and gas conference.

The 20-year-old and hundreds of people were near the InterContinental London Park Lane hotel during the "Oily Money Out" demonstration, called by pressure groups Fossil Free London and Greenpeace, blocking all entrances to the venue.

Images showed Thunberg wearing a badge with the protest slogan and standing calmly as two police officers spoke to her. One was seen holding her arm.

Other pictures showed the activist being searched and placed in the back of a police van.

"Behind these closed doors, spineless politicians are making deals and compromises with lobbyists from [the] destructive fossil fuel industry," Thunberg told the media ahead of her detention.

What was the protest for?

The demonstrators accuse fossil fuel companies of intentionally slowing the global energy transition to renewables in order to make more profit.

"The world is drowning in fossil fuels. Our hopes and dreams and lives are being washed away by a flood of greenwashing and lies," Thunberg said. "It has been clear for decades that the fossil fuel industries were well aware of the consequences of their business models, and yet they have done nothing."

"We cannot let this continue. The elite of the oil and money conference. They have no intention of transition," she said.

"We have no other option but to put our bodies outside this conference and to physically disrupt. And we have to do that every time. We have to continue showing them that they are not going to get away with this."

Meanwhile, environment groups have said they will continue to protest throughout the conference, which is scheduled to run until Thursday.

On Tuesday, two Greenpeace activists scaled the hotel building to unfurl a giant banner reading "make big oil pay." 

London's Metropolitan Police are yet to provide a statement on Thunberg. However, in a statement on social media platform X, they said that they had made 20 arrests in connection with protests outside the hotel.

This year, Thunberg has been detained by police or removed from protest rallies in Sweden, Norway and Germany.

dvv/msh (AFP, AP, Reuters)